Recurrent Syncope in Childhood 26/11/15

What is Syncope? Syncope is a temporary loss of consciousness resulting from a reversible disturbance of cerebral function. Characteristics: - loss of consciousness because of a lack of cerebral blood flow - sudden onset - transient attacks. In children, it is not uncommon (20% will experience at least one episode) and most often benign. Before the age of six years, syncope is unusual except in patients with seizure disorders, breath-holding episodes and primary cardiac dysrhythmias.

Neurally-mediated Syncope Most common cause of syncope in young patients. Related to the beta-adrenergic hypersensitivity of baroreceptors in the vessels and the mechanoreceptors of the left ventricle following - subtle changes in postural tone - change in circulating volume - direct release of catecholamine from higher cerebral centres.

NMS Features 1.Prodrome (seconds to mins) – light-headedness/dizziness/nausea/pallor/sweating 2. Brief period of unconsciousness with quick recovery 3. Precipitant -emotional stress such as fear, anxiety - sudden change in posture/anaemia/dehydration/hunger - physical exhaustion/poorly ventilated environment. Vasodepressor syncope associated with exercise has been well described in paediatric patients and most commonly occurs immediately after the termination of an activity.

Cardiac Syncope Less common than NMS but necessary to exclude. Red flags for cardiac syncope: 1. Little or no prodrome 2. Prolonged loss of consciousness (longer than 5 min) 3. Exercise-induced syncope 4. Chest pain or palpitations 5. History of cardiac disease 6. Familial history of long QT syndrome, cardiomyopathy or sudden death

Causes of Cardiac Syncope Primary Left ventricular outflow obstruction Right ventricular outflow obstruction Pulmonary hypertension Eisenmenger syndrome Cardiomyopathy

Causes of Cardiac Syncope TachyarrhythmiasBradyarrythmias Long QT syndromeSick sinus syndrome Brugada syndrome (familial ventricular fibrillation) Heart block Wolff-Parkinson-White syndrome SVT VT

Non-Cardiovascular Syncope Basilar migraine Seizures Vertigo Hyperventilation Situational (cough, micturition, stretch, hair grooming, defaecation) Breath-holding spells(6-24 months) Conversion disorder/hysteria Don’t forget pregnancy in adolescent females Orthostatic hypotension Toxic exposure – cocaine/opiates/alcohol/marijuana

Investigation Thorough clinical history and examination. Physical examination should include: - Lying and standing BP (difference >20/10mmHg significant) - Full cardiovascular examination ECG – focusing on QTc, T wave morphology, ventricular hypertrophy/conduction disturbance. If arrhythmia is suspected, a 24-hour tape should be performed.

Investigation In most cases, no further diagnostic tests are needed when the history, physical examination and ECG suggest NMS. Consider further diagnostic work-up if the diagnosis is unclear or if any of the following conditions exist: - exercise-induced syncope that occurs during exertion - chest pain that precedes an episode of fainting - seizure activity - recurrent syncope (more than two or three episodes - an abnormal cardiac examination.

Investigations An echocardiogram should be performed to rule out malformations or cardiomyopathies. The tilt-table test came into use as a method for the evaluation of syncope of unknown cause. Its use is controversial in paediatrics because several groups have demonstrated sensitivities of 43% to 57% and specificities of 83% to 100%. The test usually confirms the diagnosis of NMS that is detected simply on the basis of history, physical examination and ECG. For exercise-induced syncope, an exercise stress test is mandatory to look for st-T wave changes that are associated with coronary insufficiency and catecholamine-sensitive dysrhythmias.

Management of NMS 1.Conservative management -early recognition of prodromal symptoms and intervention -avoidance of dehydration, prolonged periods of standing and irregular mealtimes. -Salt and water intake to increase plasma volume 2. Pharmacological - Beta-blocker - Fludrocortisone.

Management of Cardiac Syncope Targeted at the underlying cause. May include: 1. Beta-blockers 2. Surgical resection of obstructive lesions 3. Pacemaker insertion 4. Implantable defibrillator

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